A broken rail was the probable cause of a flaming freight train derailment and subsequent bridge collapse in Tempe nearly two years ago, the National Transportation Safety Board said in its investigation report released Thursday.
Twelve carriages derailed after the train hit a bridge over Tempe Town Lake, causing it to partially collapse and sparking a massive fire on July 29, 2020.
There were no fatalities, but several cars transporting hazardous materials overturned, chemical leaks in the area. It cost Union Pacific $11 million to replace the bridge and make other repairs.
In its completed investigation, the NTSB said it determined that the probable cause of the derailment and bridge collapse was a broken rail located on the ballast deck portion of the wooden trestle approach approximately 30 feet from the bridge. in steel.
“The lack of an interior guardrail preceding the steel bridge structure contributed to the severity of the derailment, which allowed derailed equipment to move laterally into the bridge structure and cause it to collapse” , the report adds.
The derailment happened around 6 a.m. and involved 12 of the 97 cars at the south end of the bridge, which was built in 1912.
Five of the derailed cars were tankers carrying various hazardous materials and one released about 2,200 gallons of cyclohexanone, a flammable liquid that created a pool of hazardous materials under the damaged deck.
Derailed wooden cars, which remained on the bridge, caught fire during the derailment. A firefighter was treated for smoke inhalation at the scene.